In a conventional motor armature coil winding machine, a flier is turned around an armature core and coil wire is wound around different core teeth as the armature core is indexed as required. Between the steps of each coil winding operation for each coil as well as at the start and end of the coil winding operation for each armature core, it is necessary to hook the wire around tangs attached to the segments of a commutator. A typical example of such a motor armature coil winding machine is disclosed in U.S. Pat. No. 3,506,864.
In such a coil winding machine, should any failure or error occur to the coil winding operation, for instance a failure to hook the wire around a tang or a failure to pass the wire successfully into a slot between adjacent core teeth, it is desired to stop the operation of the coil winding machine in order to prevent production of a defective armature and to minimize loss of coil wire. When a defective armature is conveyed to a next motor fabrication station without being detected, it could lead to an even more serious failure of the motor fabrication system.
It is therefore desired to monitor the state of coil windings as they are being wound around armature core teeth. Conventionally, it has been monitored by human eyes, and it was not possible to totally eliminate the possibility of overlooking defective motor armatures.